Interpretive Summary: The atmospheric concentration of carbon dioxide and other greenhouse gases is increasing. Much of the research on reducing greenhouse gas emissions has been conducted in row crop and forest systems with little emphasis on the specialty crop industries such as ornamental horticulture. Our findings indicate that dibbling fertilizer may reduce total trace gas emissions (CO2, CH4, and N2O collectively). Dibbling reduced CO2 loss compared with incorporation and topdress fertilizing methods. Dibbling and topdressing also significantly lowered N2O emissions (68 and 70%, respectively) compared to incorporation. While dibbling also resulted in lower CH4 emissions than topdressing, the fact that CH4 release was low with all methods, indicate that CH4 is not a trace gas of concern in container production systems regardless of method employed. These findings begin to provide evidence of mitigation strategies which can be used in container plant production to help growers benefit from carbon offset programs, adapt to future legislation, and improve the environmental impact from container plant production without negatively affecting plant growth.

Technical Abstract:
Increased trace gas emissions of carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) are widely believed to be a primary cause of global warming. Agriculture is a large contributor to these emissions; however, its role in climate change is unique in that it can act as a source of trace gas emissions or it can act as a major sink. Further, agriculture can significantly reduce emissions through changes in production management practices. Much of the research on agriculture’s role in mitigation of greenhouse gas (GHG) emissions has been conducted in row crops and pastures, as well as forestry and animal production systems with little focus on contributions from specialty crop industries such as horticulture. Our objective was to determine efflux patterns of CO2, CH4, and N2O associated with three different fertilization methods (dibble, incorporate, and topdress) commonly used in nursery container production. Weekly measurements indicated that CO2 fluxes were slightly lower when fertilizer was dibbled compared to the other two methods. Nitrous oxide fluxes were consistently highest when fertilizer was incorporated. Methane flux was generally low with few differences among treatments. Results from this study begin to provide data which can be used to implement mitigation strategies in container plant production which will help growers adapt to possible emission regulations and benefit from future GHG mitigation or offset programs.